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Pluto: Planet or ? Round Moons Orbit tilted to plane of solar system Orbit more elliptical than other planets Sometimes Pluto is closer to sun than Neptune Denser than Jovians, less dense than Terrestrials One of many objects orbiting sun beyond Neptune

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Meteoroids/Asteroids *Orbit the sun *Orbit the sun *Mostly between Mars and Jupiter (Some throughout the solar system) *Mostly between Mars and Jupiter (Some throughout the solar system) *Rocky, sometimes icy *Rocky, sometimes icy *Most are oblong *Most are oblong *Larger ones often called asteroids *Larger ones often called asteroids Gaspra

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Largest asteroid, Ceres, at ~600 mi. is a dwarf planet Largest asteroid, Ceres, at ~600 mi. is a dwarf planet 2 nd largest asteroid, Vesta, at ~300 mi. but not as round or massive, so it remains an asteroid 2 nd largest asteroid, Vesta, at ~300 mi. but not as round or massive, so it remains an asteroid *Meteoroids Small (grain size) to Minnesota size

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Chelyabinsk Meteor Still from a video of the Chelyabinsk meteor streaking across the sky. The video is available at https://www.youtube.com/watch?v=SMnZr5DDRlA https://www.youtube.com/watch?v=SMnZr5DDRlA

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Why study meteorites? *Possible catastrophes for us *Possible catastrophes for us

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Why study meteorites? *Summary: Composition of Moon, Mars, & asteroids Composition of Moon, Mars, & asteroids Estimate origin and age of solar system Estimate origin and age of solar system Origin of life Origin of life Possible catastrophes for us Possible catastrophes for us

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Reminder: Meteors and comets seen for different reasons Reminder: Meteors and comets seen for different reasons Meteors: In Earth’s atmosphere Comets: Not in Earth’s atmosphere

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*Meteor Shower Comet leaves trail of ice and dust Comet leaves trail of ice and dust Earth sweeps through the comet dust Earth sweeps through the comet dust See 10s to 100s of meteors per hour See 10s to 100s of meteors per hour http://astrobob.areavoices.com/2011/10/19/orionid-meteor-shower- could-make-your-wildest-dreams-come-true/